I've been told by various sources that WD40 is bad for your chain so have avoided using it. I've seen people using GT85 on their chains but I'm not really sure how the two products differ. So my question is, should GT85 be used on your chain? Or, does it have the same damaging effects as WD40?

Since I went for gearbox oil (cheap, thick, longlasting, available everywhere, one liter lasts forever) my chains look me with gratitude each time I look at them.
–
heltonbikerNov 23 '11 at 3:00

WD40 and GT85 aren't bad for your chain if used properly, which is to say for cleaning it. They're just not suitable lubricants.
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UselessSep 28 '12 at 11:07

WD40 is not a particularly good lubricant. GT85 makes a Teflon-containing bike-specific lube which is presumably "OK" if you need a very "dry" lube (though probably better for cables than chains). Hard to say about other GT85 products.
–
Daniel R HicksSep 28 '12 at 12:35

8 Answers
8

It appears that there are several products under this name, a general-purpose solvent/protectant and a dedicated bike chain lube.
Reviews on Amazon are rather mixed... One fellow claims no better than WD-40, others appear to like it.
Chain lubes are always controversial and seldom tested in a rigorous manner.

WD-40 is essentially a cleaner/solvent and has no more lubricating ability than say...Kerosene.
The best chain lube I ever tried is sadly not being made any more... Schwinn Factory Wax.

Clean-running, persistent, and according to testing by Bicycling magazine, among the top for wear and abrasion resistance.

To my way of thinking, keeping the chain clean and free of built-up crud and goo is as/more important than what sort of lube used.

Don't bother with spray lube. It takes only seconds to apply lube from a drip container. I highly recommend ProGold.

Spraying on lube makes a mess, gets lube on the outer plates of your chain (where it will just collect dirt and grime), and is wasteful to boot. Just prop your bike up, turn the drip container upside down, touch it to a link, apply a little pressure, and rotate your cranks backward at a medium speed. You might want to start slowly at first, but eventually you get a feel for how quickly lube gets sucked into the chain. I don't bother counting links, I just take a quick glance to make sure the links about to go under the bottle are already lubed. Spin the cranks a bit to make sure the lube works its way into the links, and finally grab the chain with a used rag and spin the cranks until the rag stops collecting dirt. I squeeze the sides of the plates and get them, then I do it again for the tops and bottoms.

Total time is maybe a minute and a half, and an $8 bottle of lube lasts me for months of weekly application.

I've used GT85 on chains and general bike use for years. Unlike WD40 it is loaded with PTFE (Teflon) so does have some lubrication properties but they are very small. As far as I'm aware it should be treated like WD40 primarily as a water dispersant after cleaning or wet weather riding. I always supplement it with proper chain lube (either dry or wet depending on the bike and conditions).

I am sure WD40 lubricates sufficiently if its present in clean lab conditions, however it does not stick very well and any quantity applied is really thin so will not hang around very long.

From a chain grease you want it to stay between the rubbing surfaces and continue lubricating. You also want it blocking as much dirt from contaminating the contact surfaces sealing them from contamination which WD40 or other thin oil will never do.

WD40/GT85 and other thin oil will wash off in rainy wet conditions, and not lubricate or protect the chain for very long.

Something thicker is going to be better, also keep in mind that a road bike will work well with a thinner oil/grease then some off road bike being cycled through a swamp.

Most online stores don't write their own product descriptions, but rather get the descriptions from companies who's sole purpose it is to write up product descriptions. They don't really know anything about the product but rather just write whatever they can get from the manufacturer or from the product packaging. So, basically, if it says it's works as an excellent chain lubricant it's probably because that's how the manufacturer wanted it to be marketed, and not because the store thinks it is actually an "excellent chain and cable lubricant". This is why reading reviews is so important.
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KibbeeSep 28 '12 at 12:25

I remember a bike magazine in UK recommending GT85 (its a glorified WD40, with the addition of Teflon in it) and they got slammed as the stuff was just not up to scratch, especially for Mountain Bikes.

Oh My God! WD-40 is not a Lubricant! It is Water Dispersant-40th Formula. It was developed for the space race in the 50's to displace water to prevent corrosion due to moisture condensing on metal. It forms a hydrophobic coating not a coating of lubricant. Just because anyone can buy Duct Tape and WD-40 and use it on and for anything and everything doesn't mean you should. It' means that person doesn't know anything.